Turbomachine

ABSTRACT

A turbomachine having a rotor assembly, a stator assembly and a toroidal inductor. The rotor assembly includes an impeller. The inductor is located between the impeller and the stator assembly, and is exposed to an airflow generated by or acting upon the impeller.

REFERENCE TO RELATED APPLICATIONS

This application claims the priority of United Kingdom Application No.1114789.9, filed Aug. 26, 2011, the entire contents of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a turbomachine.

BACKGROUND OF THE INVENTION

The circuit assembly of a turbomachine may include an inductor forsmoothing current ripple. The physical size of the inductor is oftenrelatively large and thus impacts on the overall size of theturbomachine.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides a turbomachinecomprising a rotor assembly, a stator assembly, and a toroidal inductor,wherein the rotor assembly comprises an impeller, and the inductorsurrounds the rotor assembly, is located between the impeller and thestator assembly, and is exposed to an airflow generated by or actingupon the impeller.

By employing a toroidal inductor that surrounds the rotor assembly andis located between the stator assembly and the impeller, a relativelycompact turbomachine may be achieved. Additionally, since the inductoris exposed to the airflow generated by or acting upon the impeller,copper loses may be reduced.

The rotor assembly may comprise a shaft to which a rotor core, a bearingassembly and the impeller are mounted. The bearing assembly is thenlocated between the rotor core and the impeller, and the inductorsurrounds the bearing assembly. By mounting the impeller and the rotorcore on opposite sides of the bearing assembly, a relatively compactrotor assembly is achieved. By employing a toroidal inductor thatsurrounds the bearing assembly, good use is made of the available spacearound the bearing assembly.

The turbomachine may comprise a circuit board to which the inductor iselectrically coupled, and the stator assembly may be located between thecircuit board and the inductor. By locating the circuit board in thisway, the circuit board may be isolated from the airflow, if required.Alternatively, the circuit board may be exposed to the airflow but,owing to its location, does not adversely interfere or restrict theairflow.

The turbomachine may comprise a shroud that covers the impeller, and theinductor may surround the shroud. By surrounding the shroud, theinductor makes good use of the available space around the shroud. Theinner diameter of the inductor may be smaller than the outer diameter ofthe impeller. As a result, the inductor surrounds the shroud whilstremaining radially compact

In a second aspect, the present invention provides a turbomachinecomprising an impeller, a shroud covering the impeller, and a toroidalinductor that surrounds the shroud.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the present invention may be more readily understood, anembodiment of the invention will now be described, by way of example,with reference to the accompanying drawings, in which:

FIG. 1 is a sectional view of a turbomachine in accordance with thepresent invention; and

FIG. 2 is an exploded view of the turbomachine.

DETAILED DESCRIPTION OF THE INVENTION

The turbomachine 1 of FIGS. 1 and 2 comprises a housing 2, a rotorassembly 3, a stator assembly 4, and a circuit assembly 5.

The housing 2 comprises a main body 6, an upper cover 7, and a lowercover 8. The main body 6 comprises an internal frame that supports therotor assembly 3, the stator assembly 4, and the circuit assembly 5. Theupper cover 7 is secured to a first end of the main body 6 and comprisesan inlet 9 through which a working airflow is admitted. The lower cover8 is secured to a second end of the main body 6 and comprises diffuservanes 10 and an outlet 11 through which the working fluid is discharged.

The rotor assembly 3 comprises a shaft 12, a rotor core 13, a bearingassembly 14, an impeller 15 and a shroud 16. The rotor core 13, thebearing assembly 14 and the impeller 15 are each mounted to the shaft12. The shroud 16 is mounted to the bearing assembly 14 so as to coverthe impeller 15. The rotor assembly 3 is mounted to the main body 6 ofthe housing 2 at the bearing assembly 14 and at the shroud 16. Moreparticularly, the rotor assembly 3 is soft mounted at each location byan o-ring 17.

The stator assembly 4 comprises a pair of stator cores 18 arranged onopposite sides of the rotor core 13. Conductive wires 19 are wound aboutthe stator cores 18 and are coupled together to form a phase winding.The phase winding is then electrically coupled to the circuit assembly5.

The circuit assembly 5 comprises a circuit board 20 and a plurality ofelectrical components 21. The circuit board 20 is located on a side ofthe stator assembly 4 distal to the impeller 15, i.e. the statorassembly 4 is located between the circuit board 20 and the impeller 15.The circuit board 20 lies in a plane that is perpendicular to therotational axis of the rotor assembly 3; this then provides an axiallycompact arrangement. Among the electrical components 21 is a toroidalinductor 22. The inductor 22 surrounds the rotor assembly 3 and islocated between the stator assembly 4 and the impeller 15. The windingof the inductor 22 then extends axially past the stator assembly 4 andis electrically coupled to the circuit board 20.

During operating of the turbomachine 1, the impeller 15 draws airthrough the interior of the housing 2 from the inlet 9 to the outlet 11.The airflow generated by the impeller 15 passes over and cools thestator assembly 4. The interior of the housing 2 is shaped so that theairflow, after passing over the stator assembly 4, is guided towards theinlet of the shroud 16. To this end, the main body 6 of the housing 2comprises a radial flange 23 that extends inwardly from an outer wall.The inductor 22 is located below this flange 23 and thus relativelylittle of the airflow passes over the inductor 22. Nevertheless, theinductor 22 is exposed to the airflow (i.e. the inductor 22 is notisolated from the airflow) and is therefore cooled to some degree by theairflow. If increased cooling of the inductor 22 is required, thelocation of the inductor 22 and/or the interior of the housing 2 may beshaped so that the inductor 22 is exposed to more of the airflow. Forexample, the radial flange 23 may be shortened or removed altogether.Since both the stator assembly 4 and the inductor 22 are exposed to theairflow, copper losses are reduced and thus a more efficientturbomachine 1 is achieved.

By employing a toroidal inductor 22 that surrounds the rotor assembly 3and is located between the stator assembly 4 and the impeller 15, arelatively compact turbomachine 1 is achieved. In contrast, the circuitassembly of a conventional turbomachine might include an inductor (e.g.an E-core inductor) mounted directly on the circuit board. Owing to thephysical size of the inductor, the overall size of the turbomachine isincreased. Indeed, owing to the size of the inductor, it may benecessary to locate the circuit assembly remotely from the remainder ofthe turbomachine. The turbomachine 1 of the present invention, on theother hand, makes use of the space between the stator assembly 4 and theimpeller 15 to locate a toroidal inductor 22. As a result, a morecompact turbomachine 1 is achieved. Additionally, the circuit assembly 5may be mounted within the housing 2 of the turbomachine 1. This thensimplifies the mounting of the turbomachine 1 within a product. Inparticular, it is not necessary to mount the turbomachine and thecircuit assembly separately within the product and then establishelectrical connections between the two.

The bearing assembly 14 is located between the rotor core 13 and theimpeller 15. As a result, the rotor assembly 3 is relatively compact inthe axial direction. A further advantage of this arrangement is that therotor assembly 3 can be dynamically balanced as a complete unit prior tomounting within the housing 2. The inductor 22 occupies the space aroundthe bearing assembly 14. Since the stator assembly 4 and the impeller 15are radially larger than the bearing assembly 14, the introduction ofthe inductor 22 does not increase the overall size (i.e. the axiallength or maximum outer diameter) of the turbomachine 1.

The inductor 22 surrounds not only the bearing assembly 14 but also theshroud 16. The outer diameter of the impeller 15 increases from theinlet to the outlet of the impeller 15. The outer diameter of the shroud16 likewise increases from the inlet to the outlet. By surrounding theshroud 16, the inductor 22 makes good use of the available space aroundthe shroud 16. Moreover, the inner diameter of the inductor 22 issmaller than the outer diameter of the impeller 15. As a result, theinductor 22 surrounds the shroud 16 whilst remaining radially compact.

The circuit board 20 is located on a side of the stator assembly 4distal to the impeller 15 and the inductor 22, i.e. the stator assembly4 is located between the circuit board 20 and the impeller 15/inductor22). By locating the circuit board 20 in this way, the circuit board 20does not adversely interfere with the airflow passing through thehousing 2. Although the circuit board 20 does not adversely interferewith the airflow, the circuit assembly 5 is nevertheless exposed to theairflow and thus electrical components 21 mounted on the circuit board20 may be cooled. If required, the circuit board 20 may be isolated fromthe airflow. This may be necessary, for example, if the airflow islikely to carry liquid that might short or otherwise damage electricalcomponents 21 on the circuit board 20. Owing to the location of thecircuit board 20, the circuit board 20 may be isolated whilst the statorassembly 4 and the inductor 22 continue to be exposed to the airflow.

In the embodiment described above, the impeller 15 generates an airflowand thus the turbomachine 1 acts as a compressor. Alternatively, anairflow may act upon the impeller 15 such that the turbomachine 1 actsas a turbine.

1. A turbomachine comprising a rotor assembly, a stator assembly, and atoroidal inductor, wherein the rotor assembly comprises an impeller, andthe inductor surrounds the rotor assembly, is located between theimpeller and the stator assembly, and is exposed to an airflow generatedby or acting upon the impeller.
 2. The turbomachine as claimed in claim1, wherein the rotor assembly comprises a shaft to which a rotor core, abearing assembly and the impeller are mounted, the bearing assemblybeing located between the rotor core and the impeller, and the inductorsurrounds the bearing assembly.
 3. The turbomachine as claimed in claim1, wherein the turbomachine comprises a circuit board, the inductor iselectrically coupled to the circuit board, and the stator assembly islocated between the circuit board and the inductor.
 4. The turbomachineas claimed in claim I, wherein the turbomachine comprises a shroud thatcovers the impeller, and the inductor surrounds the shroud.
 5. Theturbomachine as claimed in claim 4, wherein the inner diameter of theinductor is smaller than the outer diameter of the impeller.
 6. Aturbomachine comprising an impeller, a shroud covering the impeller, anda toroidal inductor that surrounds the shroud.
 7. The turbomachine asclaimed in claim 6, wherein the inner diameter of the inductor issmaller than the outer diameter of the impeller.